This annual renewal proposal has been prepared by an interdisciplinary project group with over a decade of experience in laboratory and clinical use of assisted circulation. The objectives are: 1. The continuation of an interdisciplinary laboratory program for the study and development of mechanical cardiorespiratory support which is complemented by a parallel but coordinated program at Rice University, and includes faculty and graduate students at the University of Houston. 2. The major thrust of the program has not been solely device development, but rather the interaction of the living organism with the device. Projects have included a clinical study of mechanical cardiorespiratory support, evaluation of prototype devices in animals, evaluation of the impact of devices on circulatory cybernetics, development of prototype devices, study of flow dynamics in circulatory prostheses, study of synthetic and biomacromolecules, and of specific cell function (e.g., blood).